Server crashing sometimes from large values in twkb encoding

[nicklas]

The attached geometry writes beyond the buffer.

In some cases it crashes the server.

It is caused from a large value that encodes to a variable integer of 10 bytes instead of the expected max 8 bytes. Most of the time this doesn't do any harm. But if the preceding point leaves exactly 8 bytes left in the buffer, the space check will not reallocate and writing 9 or 10 bytes will cause writing beyond the buffer.

[nicklas]

increased the expected max size of variable integer to 16 bytes instead of 8 bytes.

That should always be enough since the value gets truncated by casting to int64_t before encoding to variable integer

fixed in trunk r15817

[nicklas]

fixed in 2.2 and 2.3 with r15836 and r15837

[robe]

need to put this in NEWS for 2.2 and 2.3. For 2.4 not necessary.

[pramsey]

In 15838:

TWKB news item (References #3866)

[pramsey]

In 15839:

TWKB news item (Closes #3866)